Investing in new lights LED or HID?

[SupraSPL]

Someone mentioned the Hortilux super HPS as the best choice. I also noticed secondtry mention UVB and UVC on one of these threads. As far as I understand our atmosphere filters out UVC at ground level. It is hard to imagine how UVC could contribute anything to marijuana. DNA has an absorption peak at ~260nm UVC. The spectral analysis graphs I have seen of sunlight show it rolling off in the UVB range at about 300nm (this curve is emulated nicely by tanning fluoros and some reptile fluoros)

So, does the Hortilux super HPS output UVB and UVC? I have experimented with the reptile UVB fluoros with good success so far. But on the other hand, I have smoked bud grown under 100% plain jane HPS which has virtually no UVB output, and I was wrecked for sure.

So there are all sorts of considerations when looking for the "perfect" lamp.

@OP. I am automaically suspicious of the LED spotlights. Their radiometric efficiency (light output per watt) and cooling is probably questionable, not to mention driver efficiency, do you have a link? A Hydro Grow LED on the other hand is a fair option for a small closet and will definitely grow some bud. The 400w HPS would work awesome as well. Good luck!

EDIT BTW with either of the choices I mentioned, you are going to LOVE the results compared to the 26w CFLs. They offer a paltry 50 lumens per watt with lots of green and weak on the red, plus they suffer from reflector losses. I am trying to get away from fluoros for vegging for good.

 

[Bud Bug]

...recently that LED isn't quite ready for prime-time yet. This isn't what the producers of LED growlamps are saying, of course. This guy had quite a few LED setups running and on display in his shops too, so he has done the work.

I had a 300W LED lent to me to test it out. On cannabis it was pretty sad for flowering but quite nice in the veg stage, although
for $1400 @300W I'd rather do with a 400W system at $200.

I also grew basil under that LED array is it was crazy how big it got.

 

[jm420]

i would go with a nextgen 400-600 if i was going to experiment, lite weight, air cooled, 5 year warranty 250 bucks cant beat that

 

[dubbalicious]

HID!!!!!

 

[superpedro]

I don't know much about the lamps you can buy on the internet, but the professional ones I see really kicks ass.

I would love to build my own, since you have to control each color and make circadian rhythm based light changes, in order to get the full effect of the new technology.
The way they can alter the development of plants is amazing.

In Danish plant nurseries there is more than 180,000m2 of greenhouse field testing going on right now, it should be affordable for the ordinary gardener by 2013. That is the advice we get. But the first commercial should be ready late 2010. (not for the home grower though )
Wonder when the serious stuff shows up in grow shops.

 

[Think Green]

just bought some new gear last month. Went with a 600hps air cooled reflector ...... & a tent.... & an r/o system...& an 8 bulb T5 ... & 400cfm fan.....& ballast. . .damn this is an expensive hobby! Made switch last month. Anyways, I grew with cfl just like you. Heres some pics from what I was doing & what Im doing now...

Last Month:

Flowering Room Before:

Flowering Room After:

Veg Room Before:

Veg Room After:

IMHO... Stick with H.I.D

 

[Think Green]

On a further note, better do some research on the digi ballast. Looked around hard before I made my investment of 2 grand. Settled on this ballast, which comes in 400w as well. Coolest, low noise ballast I've ever seen.

http://www.hydrofarm.com/pb_detail.php?itemid=3501

 

[NiteTiger]

Do yourself a favor and go with a magnetic HID light, and save yourself about a hundred bucks. Or be able to get about $100 worth of extra goodies

If you have functioning hands and basic reading skills, you could have a 1kw mag, a six inch fan, carbon scrubber, and cooltube and come in under budget.

Now, you obviously don't need 1kw, but you do need more than 400 for that space. You've got a little over 10 sq ft, which means with a 400 you're only going to get about 40 watts per sq ft. You want to aim for 50+ watts per sq ft, which means you'll want to kick up to a 600.

Which easily within budget if you do a mag ballast.

 

[Think Green]

Well put nite!

 

[secondtry]

@ SupraSPL,

I use Hortalux Super HPS but I am switching to CMH this coming grow for the better SPD and I'll use quantum sensor to place CMH so it emits 1400-1,500 PPFD.

I also use 300w reptile lamps for UV-b, I use Osram Ultra Vita lux at a daily UV-b irridiance of 200-372 uW/cm^2 (I converted the latter from 13.4 kJ/m^-2; Lydon, et al., 1986) for four hours a day near mid-day. The highest recorded irridiance level of UV-b I know of was measured to be ~530 uW/cm^2 at noon in mid summer on top of volcano on Maui, HI, just over 10k elevation. At sea level near equator in summer at midday high UV-b is ~420 uw/cm^2. UV-b can help plants like cannabis by acting upon secondary metabolites like (total) CBD and THC, along with flavinoids and accessory pigments to chlorophyll A and B. It is thought the reason UV effects drug biotype cannabis is thought to be the same reason increased Co2 effects cannabis: when cannabis and other terrestrial higher plants were evolving the UV irradiance reaching the surface of earth was higher, as was the ambient level of Co2 which was about 700-800 ppm. Adding UV has been found to increase THC content in leaf by around 40-50% and in flower by around 20-30%, along with befitting many other photo-biochemcial reactions and process.

Effects of UV upon yield of lettuce under MH, HPS, etc:

Effects of UV upon chlorophyll in lettuce under MH, HPS, etc:

I add Co2 at 750-1,000 ppm:

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I don't have any free time to post more than this post for now. But please see the following study with red, green and blue LED's, and the second paper about testing of plant response to stimuli (like light) AND please read the other links I posted below (they are a small section of the research I have read and have access to, I thought these topics would be of use here).

“EVALUATION OF LETTUCE GROWTH USING SUPPLEMENTAL GREEN LIGHT WITH RED AND BLUE LIGHT-EMITTING DIODES IN A CONTROLLED ENVIRONMENT - A REVIEW OF RESEARCH AT KENNEDY SPACE CENTER,”
http://www.actahort.org/members/showpdf?booknrarnr=711_11C​

Below are some pics on qualifying and quantifying light for plants, but first I would like to quote a friend of mine from another site, it explains why the often used figure of chlorophyll A and B absorption peaks to validate the use of LEDs is not an accurate representation because those graphs LEDs users and makers cite are created in vitro with chlorophyll extracts, not even a leaf; we want absorption, reflectance, diffusion, etc., in vivo, that is a live leaf from the field (most often). The Quantum Efficiency of wavelengths within PAR range is not reflected in graphs showing absorption peaks of chlorophyll A and B on a slide in a spectrophotometer (for example), the figures and graphs below are in vivo and are what we should use:

http://www.bio.net/bionet/mm/plant-e...er/001134.html

Dr. David R. Hershey
dh321 at PGSTUMAIL.PG.CC.MD.US
Sun Nov 3 23:39:11 EST 1996

Chlorophyll absorption spectra indicate a very low absorption of green compared to red or blue wavelengths. However, the photosynthesis action spectrum of an intact leaf indicates the rate of photosynthesis is roughly 60% as much with green light as with red and it may actually be higher than with blue (see Salisbury & Ross, Plant Physiology, 3rd, p. 185) Thus, leaves can use green light fairly effectively in photosynthesis. Some of the absorption may be due to accessory pigments. Chlorophyll in an intact leaf can also absorb green light much more effectively than the chlorophyll absorption spectrum (chlorophyll extract in a spectrophotometer) indicates. One reason is that although green light is absorbed with low efficiency, it has many chances to be absorbed because it is repeatedly reflected from cell to cell by the complex leaf geometry so it has many chances to be absorbed. Such geometry effects do not occur with chlorophyll extract in a spectrophotometer tube. This provides an excellent illustration of how in vitro can differ markedly from in vivo. Unfortunately, biology textbooks usually just publish the in vitro chlorophyll absorption spectrum rather than the in vivo photosynthesis action spectrum.

Thus, the common idea that leaves are green because they reflect ALL green light is incorrect. Most leaves reflect relatively more green light relative to red/blue wavelengths and appear green to our eyes. An exception is the blue Colorado spruce (Picea pungens 'Glauca') with bluish needles. The sensitivity of our eyes might have something to do with it too because our eyes are most sensitive to 550 nm wavelengths and much less sensitive to red or blue wavelengths.

Here is what LED developers, sellers and users often cite as proof that LEDs emit only light leafs absorb as wavelengths within the PAR range, however, I want to clarify this is really an extract of a leaf within a spectrophotometer tube, ie., in vitro (please read the caption) and absorption spectrum does not equal Quantum Yield curve (Quantum Efficiency, very similar to Photosynthesis Action Spectra). The big point LED sellers like to make the claim HID emit over 60% of light plants don't need, and that's just BS, it is only true with in virto spectrophotomerer tests (and that ain't how we grow)...

Fig 1. Chlorophyll and carotenoid absorbence of PAR wavelengths (i.e., photons) in vitro using leaf extracts in a spectrophotometer tube. This figure is often used as validation and proof by LED sellers and users and this figure *IS NOT REPRESENTATIVE* of the in vivo PAS (Photosynthesis Action Spectra) or QE (Quantum Efficiency) of wavelengths with the PAR (Photosynthetically Active Radiation) range of 400-700 nanometers.

---------------------------------------------------------------

Here are in vivo figures and graphs, please read captions for more info. Please notice that all in vivo Pn graph lines follow the same basic path, the path I tried to describe before but visuals are easier. I plan to map the PAS of cannabis with reflectance-spectroscopy, chlorophyll fluorometer, quantum sensors, etc. This will take me a few years becasue the equipment is not cheap, unless people want to donate to the cause?

Fig 2. Chlorophyll and carotenoid absorbence of PAR wavelengths (i.e., photons) in vitro using leaf extracts in a spectrophotometer tube. This figure is often used as validation and proof by LED sellers and users and this figure *IS NOT REPRESENTATIVE* of the in vivo PAS (Photosynthesis Action Spectra) or QE (Quantum Efficiency) of wavelengths with the PAR (Photosynthetically Active Radiation) range of 400-700 nanometers.

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Figure 3: Sensitivity curve of plants to radiation wavelength.

QE (quantum efficiency) of wavelengths, i.e., each wavelengths effect upon rate of photosynthesis (Pn).

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Figure 4: Sensitivity curve to radiation wavelength of the human eye.

---------------------------------------------

Fig. 5. Comparison of action spectrum and quantum yield for photosynthesis with the chloroplast absorption spectrum. Quantum yield of photosynthesis is the moles of carbon fixed per mole of photons absorbed. From Taiz and Zeiger, 1991.

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Fig 6. Absorption, reflection and transmission of light by a typical soybean leaf. I/Io refers to the radiation absorbed, transmitted or reflected relative to incident radiation at the same wavelength. From Kasperbauer, 1987.

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Fig 7. Photosynthesis action spectrum

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Here is why accurate conversion between irridiance units is not possible, i.e., watts to PPFD, umol/m^2 to PPFD, etc, etc.

1. “What are the differences between Quantum Light and Solar Radiation?,”
http://support.specmeters.com/kb/index.php?ToDo=view&catId=13&questId=111​

Here are two studies showing ideal PPFD for peak rate of photosynthesis (Pn) in cannabis as 1,300-1,500 PPFD:
(LEDs will have a very hard time offering 1,300-1,500 PPFD; most LED sellers cite under 1,000 PPFD as ideal, usally under 750 PPFD and that's BS)

1. “Thidiazuron-induced high-frequency direct shoot organogenesis of Cannabis sativa L.,”
http://springerlink.com/content/3028210397611640/

2. “Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions,”
http://www.springerlink.com/content/a3527u6018823x43/​

Co2 concentration for Pnmax and stomata

1. “Effect of Carbon Dioxide Enrichment on Photosynthesis,”
http://generalhorticulture.tamu.edu/lectsupl/print/page26.html

2. “Quantum Yields for CO2 Uptake in C3 and C4 Plants: Dependence on Temperature, CO2, and O2 Concentration,”
http://www.plantphysiol.org/cgi/content/abstract/59/1/86

3. “Variation in Quantum Yield for CO2 Uptake among C3 and C4 Plants,”
http://www.plantphysiol.org/cgi/content/abstract/73/3/555

4. “Effects of CO2 on stomatal conductance: do stomata open at very high CO2 concentrations,”
http://ntrs.nasa.gov/search.jsp?R=3...=10&Ne=25&Ns=HarvestDate%7c0&N=4294802523+126​

Photosynthesis and lighting

1. “PBIO*3110 Crop Physiology, Courses @ Plant Agriculture, University of Guelph,”
http://www.plant.uoguelph.ca/courses/pbio-3110/

2. “SUMMARY OF REACTIONS OF PHOTOSYNTHESIS AND RESPIRATION,”
http://generalhorticulture.tamu.edu/lectsupl/print/page29.html

3. “Introduction to photosynthesis,”
http://web.archive.org/web/20030828080735/www2.mcdaniel.edu/Biology/botf99/photo/i1ntrophoto.htm

4. “PROPERTIES OF LIGHT THAT ARE IMPORTANT FOR PHOTOSYNTHESIS,”
http://ncr101.montana.edu/Light1994Conf/1_1_Geiger/Geiger text.htm

5. “GUIDELINES FOR LIGHTING OF PLANTS IN CONTROLLED ENVIRONMENTS,”
http://ncr101.montana.edu/Light1994Conf/8_1_Guidelines/Guidelines text.htm
​

16 hr Daylength: Diurnal Pn, circadian rhythms and carbon assimilation

RE:
I use a 30 hour dirunal for flowering as 16/14 (on/off) with an hour of dark at noon to help reduce noon-break and amount and/or intensity of Pn-peaks, both of which are mostly due mostly to DLI (Daily Light Intregral), VPD (Vapor Pressure Deficit) and air temperature; along with replenishing Rubsico activase which is needed for high Pn. I use a 20 hour diurnal for preflowering with 8/12 (on/off) which keeps stretch to a minimum while still offering sufficient Pn. I try to also use a DIFF of 0 (zero) during preflowering to keep stretch to a minimum.

1. “SUPPLEMENTAL LIGHTING OF GREENHOUSE VEGETABLES: LIMITATIONS AND PROBLEMS RELATED TO LONG PHOTOPERIODS,”
http://www.actahort.org/members/showpdf?booknrarnr=481_54

2. “LIGHT PERIOD REGULATION OF CARBOHYDRATE PARTITIONING,”
http://ncr101.montana.edu/Light1994Conf/1_6_Janes/Janes text.htm

3. “REGULATION OF ASSIMILATE PARTITIONING BY DAYLENGTH AND SPECTRAL QUALITY,”
http://ncr101.montana.edu/Light1994Conf/1_2_Britz/Britz text.htm

4. “Factors affecting the rate of photosynthesis,”
http://web.archive.org/web/20030306020209/http://www.geocities.com/CapeCanaveral/Hall/2385/rate.htm

5. “Independent Circadian Regulation of Assimilation and Stomatal Conductance in the ztl-1 Mutant of Arabidopsis,”
http://www.jstor.org/pss/1514476

6. “Environmental effects on circadian rhythms in photosynthesis and stomatal opening,”
http://www.springerlink.com/content/m275226261246h24/

7. “Circadian Rhythms in Photosynthesis : Oscillations in Carbon Assimilation and Stomatal Conductance under Constant Conditions,”
http://www.plantphysiol.org/cgi/content/abstract/96/3/831

8. “COORDINATING PHOTOSYNTHETIC ACTIVITY: CIRCADIAN RHYTHMS,”
http://www.tiem.utk.edu/bioed/webmodules/circadianrhythm.html

9. “859.pdf,”
http://www.plantphysiol.org/cgi/reprint/102/3/859.pdf​

Noon-break phenomenon and multi-peak Pn and diurnal Pn changes

1. “Study on the Diurnal Changes of Net Photosynthetic Rate and the Impact Factors of Stevia rebaudiana Bertoni in Autumn,”
http://www.scialert.net/pdfs/ajpp/2009/18-23.pdf

2. “DAILY CHANGES IN THE PHOTOSYNTHETIC RATE AND CHLOROPHYLL FLUORESCENCE IN FOUR COLORED LEAF PRUNUS TAXA,”
http://www.actahort.org/books/769/769_56.htm

3. “Effects of different light transmission rate on American ginseng's photosynthesis,”
http://www.ncbi.nlm.nih.gov/pubmed/15146635

4. “Physiology of woody plants,”
http://books.google.com/books?id=lE...summary_r&cad=0#v=snippet&q=peak noon&f=false

5. “Diurnal changes in net photosynthetic rate in potato in two environments,”
http://www.springerlink.com/content/t7k256132141w668/

6. “lec21.pdf,”
http://www.plant.uoguelph.ca/courses/pbio-3110/documents/lec21.pdf​

Rubisco

1. “When the Lights Go Out"
(note: blue PAR photons do not offer grater Pn than red PAR photons)
http://thegardeninghub.spaces.live.com/blog/cns!3413DF10CC8C202A!231.entry

2. “Robust Plants' Secret? Rubisco Activase!,”
http://www.ars.usda.gov/is/AR/archive/nov02/plant1102.htm
​

The great series by Sanjay Yoshi, Ph.D.:

1. "Part I: What is light?"
http://www.reefkeeping.com/issues/2006-02/sj/index.php

2. "Part II: Photons"
http://www.reefkeeping.com/issues/2006-03/sj/index.php

3. "Part III: Making Sense of Light Measures"
http://www.reefkeeping.com/issues/2006-04/sj/index.php

4. "Part IV: Color Temperature"
http://www.reefkeeping.com/issues/20...sj/index.php#0

5. "Part V: Everything You Need to Know About Metal Halide Lamps and Ballasts"
http://www.reefkeeping.com/issues/2007-03/sj/index.php
​

Light quality (PAR) and quantity (PPFD)

1. “Effect of atmospheric turbidity on the photosynthetic rates of leaves,”
http://www.sciencedirect.com/scienc...serid=10&md5=6a6fd5b02483e7a7ee1ee1433c0cf531

2. “SPECTRAL DEPENDENCE OF PHOTOSYNTHESIS IN CROP PLANTS,”
http://www.actahort.org/books/87/87_18.htm

3. “Carotenoid-to-Chlorophyll Energy Transfer in Recombinant Major Light-Harvesting Complex (LHCII) of Higher Plants. I. Femtosecond Transient Absorption Measurements,”
http://gbb.eldoc.ub.rug.nl/root/2001/BiophysJCroce/?pFullItemRecord=ON

4. “The spectrum [of absorption] and photosynthesis,”
http://web.archive.org/web/20080512...uwc.ac.za/ecotree/photosynthesis/spectrum.htm

5. “Reductions in mesophyll and guard cell photosynthesis impact on the control of stomatal responses to light and CO2,”
http://www.ncbi.nlm.nih.gov/pubmed/18836187?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=1&log$=relatedarticles&logdbfrom=pubmed

6. “LEAF ABSORBANCE AND PHOTOSYNTHESIS,”
http://ncr101.montana.edu/Light1994Conf/1_7_Schurer/Schurer Photosyn.htm

7. “EFFECTS OF RADIATION QUALITY, INTENSITY, AND DURATION ON PHOTOSYNTHESIS AND GROWTH,”
http://ncr101.montana.edu/Light1994Conf/1_5_Bugbee/Bugbee text.htm

8. “OPTIMIZATION OF LAMP SPECTRUM FOR VEGETABLE GROWTH,”
http://ncr101.montana.edu/Light1994Conf/1_4_Prikupets/Prikupets text.htm

9. “SPECTRAL COMPOSITION OF LIGHT AND GROWING OF PLANTS IN CONTROLLED ENVIRONMENTS,”
http://ncr101.montana.edu/Light1994Conf/1_3_Tikhomirov/Tikhomirov text.htm

10. “EVALUATION OF LETTUCE GROWTH USING SUPPLEMENTAL GREEN LIGHT WITH RED AND BLUE LIGHT-EMITTING DIODES IN A CONTROLLED ENVIRONMENT - A REVIEW OF RESEARCH AT KENNEDY SPACE CENTER,”
http://www.actahort.org/members/showpdf?booknrarnr=711_11

11. “Photosystem I and II and the Light Reaction,”
http://web.archive.org/web/20030824121436/www2.mcdaniel.edu/Biology/botf99/photo/l4ightrx.html

12. “The Nature of Light,”
http://web.archive.org/web/20030831211105/www2.mcdaniel.edu/Biology/botf99/photo/l2inature.htm

13. “Photosynthisis Action Spectrum (image),”
http://web.archive.org/web/20020424....maricopa.edu/bio/bio181/BIOBK/absorspect.gif

14. “Regulation of photosynthesis by light quality and its mechanism in plants,”
http://www.ncbi.nlm.nih.gov/pubmed/18839928

15. “Green Light Drives Leaf Photosynthesis More Efficiently than Red Light in Strong White Light: Revisiting the Enigmatic Question of Why Leaves are Green,”
http://pcp.oxfordjournals.org/cgi/content/full/50/4/684

16. “EFFECT OF LIGHT INTENSITY AND CO2 ON PHOTOSYNTHESIS,”
http://generalhorticulture.tamu.edu/lectsupl/print/page26.html

17. “EFFECT OF LIGHT QUALITY ON PHOTOSYNTHESIS,”
http://generalhorticulture.tamu.edu/lectsupl/print/page25.html

18. “FACTORS AFFECTING PHOTOSYNTHESIS,”
http://generalhorticulture.tamu.edu/lectsupl/print/page24.html

19. “All colours in light are equal for photosynthesis,”
http://www.agriworld.nl/public/file/pdf/20060504-fltcs7.2.pdf

20. “Photosynthetic Characteristics of Rice Leaves Grown under Red Light with or without Supplemental Blue Light,”
http://pcp.oxfordjournals.org/cgi/content/abstract/45/12/1870
​

Green light, chlorophyll and accessory pigments (e.g., carotenoids):

1. “Plant Pigments that absorb light,”
http://www.kadasgarden.com/Cpigments.html

2. “Plant Pigment - Carotenoids,”
http://science.jrank.org/pages/5303/Plant-Pigment-Carotenoids.html

3. “Carotenoids as Flavor & Fragrance Precursors,”
http://www.leffingwell.com/caroten.htm

4. “Carotenoids in Light Harvesting Complexes,”
http://www.leffingwell.com/lhc.htm

5. “photosynthesis pigments,”
http://web.archive.org/web/20030824121542/www2.mcdaniel.edu/Biology/botf99/photo/p3igments.html

6. “Absorption Spectrum of Chlorophyll and Carotenoids,”
http://generalhorticulture.tamu.edu/lectsupl/Physiol/physiol.html

7. “Chlorophyll and Green Light (1),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001129.html

8. “Chlorophyll and Green Light (2),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001134.html

9. “Chlorophyll and Green Light (3),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001128.html

10. “Chlorophyll and Green Light (4),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001132.html

11. “Chlorophyll and Green Light (5),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001140.html

12. “Chlorophyll and Green Light (6),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001205.html

13. “separation of plant pigments (1),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001146.html

14. “separation of plant pigments (2),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001153.html

15. “separation of plant pigments (3),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001155.html

16. “Pigment changes - WHY?,”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001198.html

17. “"safe" green light (1),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001331.html

18. “"safe" green light (2),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001334.html

19. “"safe" green light (3),”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001344.html

20. “Will green light kill your plants?,”
http://www.exoticrainforest.com/Will green light kill.html

21. “Green light, best for the Photosynthesis,”
http://www.ubcbotanicalgarden.org/forums/showthread.php?p=236473

22. “Chlorophyll, Photosynthesis,Photons,”
http://www.physicspost.com/physicsforums/topic.asp-ARCHIVE=&TOPIC_ID=6892.htm

23. “Photosynthesis,”
http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect10.htm

24. “Carotenoids in photosynthesis: an historical perspective,”
http://d.wanfangdata.com.cn/NSTLHY_NSTL_HY1704989.aspx
​

UV-b and UV-c

1. “UV-B RADIATION EFFECTS ON PHOTOSYNTHESIS, GROWTH and CANNABINOID PRODUCTION OF TWO Cannabis sativa CHEMOTYPES,”
http://www3.interscience.wiley.com/journal/120019839/abstract

2. “Influence of PAR and UV-A in Determining Plant Sensitivity and Photomorphogenic Responses to UV-B Radiation,”
http://findarticles.com/p/articles/mi_qa3931/is_200404/ai_n9345790/

3. “Photochemical studies of marijuana (Cannabis) constituents,”
http://www3.interscience.wiley.com/journal/113338818/abstract

4. “Chemical ecology of Cannabis,”
http://www.hempfood.com/Iha/iha01201.html

5. “UV Guide UK - UVB reptile lighting on test,”
http://www.uvguide.co.uk/index.htm

6. “Specificity and Photomorphogenic Nature of Ultraviolet-B-Induced Cotyledon Curling in Brassica napus L.,”
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC158827/

7. “Ultraviolet B radiation enhances a phytochrome-B-mediated photomorphogenic response in Arabidopsis,”
http://www.ncbi.nlm.nih.gov/pubmed/...roller.PPMCArticlePage.PPMCPubmedRA&linkpos=1

8. “Ultraviolet wavelength dependence of photomorphological and photosynthetic responses in Brassica napus and Arabidopsis thaliana,”
http://www.ncbi.nlm.nih.gov/pubmed/...roller.PPMCArticlePage.PPMCPubmedRA&linkpos=3

9. “UV-B Radiation, Photomorphogenesis and Plant-Plant Interactions,”
http://www.springerlink.com/content/p8206130h2122547/

10. “LIGHTING CONSIDERATIONS IN CONTROLLED ENVIRONMENTS FOR NONPHOTOSYNTHETIC PLANT RESPONSES TO BLUE AND ULTRAVIOLET RADIATION,”
http://ncr101.montana.edu/Light1994Conf/3_1_Caldwell/Caldwell text.htm

11. “UV-A/BLUE-LIGHT RESPONSES IN ALGAE,”
http://ncr101.montana.edu/Light1994Conf/3_2_Senger/Senger text.htm

12. “REQUIREMENTS OF BLUE, UV-A, AND UV-B LIGHT FOR NORMAL GROWTH OF HIGHER PLANTS, AS ASSESSED BY ACTION SPECTRA FOR GROWTH AND RELATED PHENOMENA,”
http://ncr101.montana.edu/Light1994Conf/3_3_Hashimoto/Hashimoto text.htm

13. “Screening of visible and UV radiation as a photoprotective mechanism in plants,”
http://www.springerlink.com/content/g82t5p3k803p3162/

14. “Field testing of biological spectral weighting functions for induction of UV-absorbing compounds in higher plantst,”
http://cat.inist.fr/?aModele=afficheN&cpsidt=15756317
​

IR: Red Photons (Phytochrome)

1. “PHYTOCHROME, PLANT GROWTH AND FLOWERING,”
http://ncr101.montana.edu/Light1994Conf/2_4_King/King text.htm

2. “PLANT PHOTOMORPHOGENESIS AND CANOPY GROWTH,”
http://ncr101.montana.edu/Light1994Conf/2_3_Ballare/Ballare Text.htm

3. “HISTORY AND APPLICATIONS IN CONTROLLED ENVIRONMENTS,”
http://ncr101.montana.edu/Light1994Conf/2_2_Downs/Downs Text.htm

4. “IMPLICATIONS FOR CONTROLLED ENVIRONMENT RESEARCH FACILITIES,”
http://ncr101.montana.edu/Light1994Conf/2_1_Smith/Smith text.htm​

Quantum Use Efficiency, Quantum Flux Density, Yield Photon Flux, etc

1. “The measurement of photosynthetically active radiation,”
http://www.sciencedirect.com/scienc...serid=10&md5=960f932e50ed5909795d4160c8b7b3b9

2. “Test of current definitions of photosynthetically active radiation against leaf photosynthesis data,”
http://www.sciencedirect.com/scienc...serid=10&md5=95e63cf68abfa299f3f999d16b9da48f

3. “Action spectra for photosynthesis in higher plants,”
http://pcp.oxfordjournals.org/cgi/reprint/17/2/355.pdf

4. “SPECTRAL DEPENDENCE OF PHOTOSYNTHESIS IN CROP PLANTS,”
http://www.actahort.org/books/87/87_18.htm

5. “The action spectrum, absorptance and quantum yield of photosynthesis in crop plants,”
http://www.sciencedirect.com/scienc...serid=10&md5=0fbe2e311cc11aa643b79c2e0806622f

6. “On The Action Spectra of Photosynthesis and Spectral Depedence of the Quantum Efficiency,”
http://www.bio21.bas.bg/ipp/gapbfiles/v-26/00_1-2_58-69.pdf
​

Equipment and methods to quantitate PPFD, Pn, chlorophyll, growth analysis

1. “A transmission meter for photosynthetically active radiation,”
http://www.sciencedirect.com/scienc...serid=10&md5=ff81b9ac1a780af4bcf92b359f64c37f

2. “A PHYTOMETRIC IRRADIANCE MEASURING INSTRUMENT,”
http://www.actahort.org/members/showpdf?booknrarnr=711_57

3. “Plotting Rates of Photosynthesis as a Function of Light Quantity,”
http://www.jstor.org/pss/4450196

4. “InstrumentationHandout.pdf,”
http://www.plant.uoguelph.ca/courses/pbio-3110/documents/InstrumentationHandout.pdf



Here is why the Li-Cor quantum sensor is a good and relatively inexpensive choice:

Lamps (HID, LED, etc)

1. “SPECTRAL COMPARISONS OF SUNLIGHT AND DIFFERENT LAMPS,”
http://ncr101.montana.edu/Light1994Conf/5_1_Deitzer/Deitzer text only.htm

2. “FLUORESCENT AND HIGH INTENSITY DISCHARGE LAMP USE IN CHAMBERS AND GREENHOUSES,”
http://ncr101.montana.edu/Light1994Conf/5_3_Langhans/Langhans text.htm

3. “ENHANCEMENT OF EFFICIENCY IN THE USE OF LIGHT FOR CULTIVATION OF PLANTS IN CONTROLLED ECOLOGICAL SYSTEMS,”
http://ncr101.montana.edu/Light1994Conf/5_6_Mashinsky/Mashinsky text.htm

4. “XENON LIGHTING ADJUSTED TO PLANT REQUIREMENTS,”
http://ncr101.montana.edu/Light1994Conf/5_9_Kofferlein/Kofferlein text.htm

5. “EFFICIENT, FULL-SPECTRUM, LONG-LIVED, NON-TOXIC MICROWAVE LAMP FOR PLANT GROWTH,”
http://ncr101.montana.edu/Light1994Conf/5_10_MacLennan/MacLennan text.htm

6. “Soybean stem growth under high-pressure sodium with supplemental blue lighting,”
http://ntrs.nasa.gov/search.jsp?R=7...&qs=Ne=25&Ns=HarvestDate%7c0&N=4294802523+126

7. “[LEDs] LIGHT EMITTING DIODES AS A PLANT LIGHTING SOURCE,”
http://ncr101.montana.edu/Light1994Conf/5_11_Bula/Bula text.htm

8. “[LEDs] EVALUATION OF LETTUCE GROWTH USING SUPPLEMENTAL GREEN LIGHT WITH RED AND BLUE LIGHT-EMITTING DIODES IN A CONTROLLED ENVIRONMENT - A REVIEW OF RESEARCH AT KENNEDY SPACE CENTER,”
http://www.actahort.org/members/showpdf?booknrarnr=711_11

9. “[LEDs] Growth and photomorphogenesis of pepper plants under red light-emitting diodes with supplemental blue or far-red lighting,”
http://ntrs.nasa.gov/search.jsp?R=1...=10&Ne=25&Ns=HarvestDate%7c0&N=4294802523+126
​

Reflector

1. “Importance of a Good Reflector,”
http://www.aquariumgarden.com/info.php?doc_base=articles/lights/reflector.php
​

Why leaf are green

1. “Why are higher plants green? Evolution of the higher plant photosynthetic pigment complement,”
http://www.oxygraphics.co.uk/whygreen.pdf

2. “why are plants green?,”
http://www.bio.net/bionet/mm/plant-ed/1996-November/001121.html

3. “Why Trees are Green,”
http://www.abc.net.au/science/k2/trek/4wd/may99_1.htm

4. “whygreen.pdf,”
http://www.oxygraphics.co.uk/whygreen.pdf

5. “Why photosynthesis pigment of plant is green and not black?,”
http://www.madsci.org/posts/archives/dec2001/1008985836.Bt.r.html​

Pn, RH, leaf-to-air VPD (vapor pressure deficit):

1. “Control of Photosynthesis and Stomatal Conductance in Ricinus communis L. (Castor Bean) by Leaf to Air Vapor Pressure Deficit,”
http://www.ncbi.nlm.nih.gov/pubmed/16669054?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=4&log$=relatedarticles&logdbfrom=pubmed

2. “Relative Humidity or Vapor Pressure Deficit,”
http://www.jstor.org/pss/1931468

3. “Humidity and Vapour Pressure Deficit (VPD),”
http://www.autogrow.com/1_information/1_vpd/info_vpd.html

4. “VPD Calculator,”
http://www.autogrow.com/vpd_calc.php

5. “Measuring Vapor Pressure Deficit in the Field,”
http://biomet.ucdavis.edu/biomet/VPD/vpd.htm

6. “Influence of soil water status and atmospheric vapor pressure deficit on leaf gas exchange in field-grown winter wheat,”
http://www.linkinghub.elsevier.com/retrieve/pii/S0098847203000790

7. "Influence of temperature and leaf-to-air vapor pressure deficit on net photosynthesis and stomatal conductance in red spruce (Picea rubens),"
http://www.ncbi.nlm.nih.gov/pubmed/12651527

8. “THE INFLUENCE OF VAPOUR PRESSURE DEFICIT ON LEAF WATER RELATIONS OF COCOS NUCIFERA IN NORTHEAST BRAZIL,”
http://journals.cambridge.org/actio...1DDC139CB.tomcat1?fromPage=online&aid=3044724

9. “Influence of leaf-to-air vapour pressure deficit (VPD) on the biochemistry and physiology of photosynthesis in Prosopis juliflora,”
http://jxb.oxfordjournals.org/cgi/content/abstract/erh229v1

10. “Humidity.pdf,”
http://web.archive.org/web/20071019120201/http://www.atplas.com/films/PDF/Humidity.pdf

11. “70 WmsBaeza07.pdf,”
http://www.uckac.edu/uckac/people/PDFs/Williams/70 WmsBaeza07.pdf

12. “Ch03.pdf,”
http://ncr101.montana.edu/Growth_Chamber_Handbook/Ch03.pdf

13. “APP-EnvironTesters-Humidity.pdf,”
http://www.aemc.com/techinfo/appnotes/environmentaltesters/APP-EnvironTesters-Humidity.pdf​

 

[secondtry]

Edit: I updated the images with titles, sorry about that. All the above backup what I wrote because that is where I got the info from...

 

[whodair]

LED=Televisions

 

[secondtry]

And brake lights, etc, not for cannabis unless it's in a power limited environment. One town tried them for stop light someplace last winter and they didn't get warm enough to melt ice and snow...grab the steering wheel and go for it! ha.

 

[jm420]

second try WTF i could grow from seed to harvest with a match before i read all that shit HID is the most proven as of now ,but the new plasmas look like the real deal

 

[secondtry]

Haha, well some people like to read the 'whys', as long as you think high irridiance white light is the way to grow your alright in my book

 

[NiteTiger]

Holy wall of text Batman, er, secondtry

Good info, but I think my eyes are bleeding

 

[Blue Tail]

secondtry,

I am also considering a lighting upgrade. The Luxim plasma lights (see the .pdf for the LIFI-STA-41-02) that have been mentioned in other threads here, will be market ready with licensed horticulture versions very soon. These lights have me intrigued. Any informed opinions? I would very much appreciate your thoughts on these lights.


BT

 

[secondtry]

secondtry,

I just bumped into this thread and I will be going through all of your references, as I am also considering a lighting upgrade. Meantime... the Luxim plasma lights (see the .pdf for the LIFI-STA-41-02) will be market ready with licensed horticulture versions very soon. These lights have me intrigued. Any informed opinions? I would very much appreciate your thoughts on these lights.

Best Regards,

BT

Hmmm,

On paper it looks good, but in action I would not bet the farm. According to their data it will take (2) Solar Genesis II at 8" to reach over 1,500 PPFD, how much does that cost? The SPD is good but I like the SPD of CMH better and once I test irridiances as PPFD (by distance) other ICmag members can use that as a guide. Quantity of light (PPFD) is easy to modify to changing the distance to the conapy; quality of light (SPD) is not easy to change.

Here are some experts from their site, overall the science is based on sound, proven scientific theory, however, just don't seem to understand it fully. They do seem to understand it better than any other LED site I have seen so far. Good for them, nice to see.

FAQ:Most currently available LED Grow Lights contain two frequencies (colors) and claim that the other frequencies within the spectrum recognized for optimum plant growth are of very little value to the plant so they are ignored. Typical LED Grow Lights also have a fixed output with no control over the amount of each frequency (color) in relation to each other. Research indicates that seedlings and plants in the vegetative stage benefit from a higher percentage of light within the blue spectrum whereas plants in the bloom (or budding) stage benefit from a higher percentage of light in the red spectrum. The ability to shift the color of light from blue to red can be also beneficial when you are ready to move the plant into the bloom (or budding) stage.

I am unaware of any research calming blue for veg and red for flower, that is a claim of cannabis book authors; AFAIK it is false.

Different species of plants utilize different colors of light for photosynthesis. Having the ability to adjust the colors gives us the ability to optimize plant growth during the different stages of the plants life cycle and also allows us to maximize plant growth per plant species.

That is not accurate, higher green plants have pretty similar QEC (Quantum Efficiency Curve) and Photosynthesis Action Spectrum (PAS).




Their page on PAR is the best I have yet seen (tho I would not have written it that way):
http://www.chameleongrowsystems.com/store/science/photosynthetically-active-radiation.html


And they actually know how to report PPFD (although they use the old term PPF), however, I think they used lux or lumens to try and approximate PPFD and that isn't an approximation I would make, IMO a reasonably accurate conversation is not possible:

Approximate PPF for Chameleon™ Solar Genesis™ Grow Lights
(micromoles)

Solar Genesis II - 2000 x 2 (full spectrum)
Solar Genesis VI - 2000 x 2 (full spectrum) 400 umoles PAR LED's (augmenting full spectrum)

Measurement Taken @ 8" from Light (recommended distance from plant canopy for optimum performance)

The SPD at 8" looks good (but what did they use for a spectroradiometer?):
http://www.chameleongrowsystems.com/store/comparisons/high-pressure-sodium.html



All in all it looks better than current LEDs but not as good as CMH depending upon PPFD of CMH at 8-12"....I wish there was 600 watt or 1,000 watt CMH.

FWIW: IMO the future is pulse start CMH of higher wattage (that's if CMH emits enough PPFD at a great enough distance)

HTH

 

[secondtry]

Hmmmm,

I have been thinking about the irridiance and footprint of 400w HID such as a CMH lamp and I decided I will not buy it, nor any 400 watt HID (until I test them). As noted we want to achieve 1,300-1,500 PPFD for cannabis, and ideally the irridiance spread (footprint) over the canopy is fairly even (homogeneous) with large ares of high PPFD; the former is achieved by using high power HID at correct distance to canopy, the latter is achieved with a high quality reflector with a diffuse reflective surface (not a mirror surface, that creates hot spots and a less even irridiance spread over canopy).

Now back to 400watt HIDs: they emit lower PPFD than a 1,000 watt HID at the same distance, thus to reach ideal PPFD a 400watt would need to be placed close to canopy (as is currently suggested) but that also increases hot spot/s intensity at canopy due to light reflection issues from the reflector while decreasing footprint homogeneity. I was reviewing the work of Sanjay Yoshi, Ph.D., (number six below) and at 24" the highest irridiance from a 400 watt MH lamp (granted it was a very blue lamp) was around 711 PPFD (using a digital ballast), and while placing the lamp closer to the canopy (for example) would increase the PPFD it would also decrease the homogeneity of irridiance spread in footprint creating more intense hot spots. Conversely a 1,000 watt can be hung further away from canopy and still provide ideal PPFD while at the same time keeping footprint irridiance spread homogeneity decline to a minimum (compered to 600w or 400w).


-----------------------------------------------

My Plans For Buy New Light System:


Lamp:
HortiLux 1,000 watt MH Blue; the SPD is good especially considering green light is such a driver of Pn (rate of photosynthesis). IIRC in all the studies I have read when a HID lamp is described by wattage it is a 1,000 watt HID.

http://www.eyehortilux.com/blue.html

Reflector: (see links at bottom for lots of info on reflectors)
I am using the P.L. 1,000 watt reflector, this reflector could preform better than all others growers currently use, it does offer an air-cooled attachment but I do not plan to use it. I use a Light-Rail 3.5 light mover, higher speed. I have in room a/c with lots of air movement, thus I plan to not use a glass shield this grow. I don't like the shields because they mess up the irridiance spread over the footprint and block photons and can increase re-strike (photons bouncing back and hitting the lamp which heats it up and effects it's spectral quality). Also MH tend to be a bit cooler than HPS. I think with all those factors considered not using a glass shield is a good idea if one measures the light and also leaf temperature (with a laser-pen) to calculate VPD (Vapor Pressure Deficit) trying to keep VPD low; the goal is to limit or totally prevent photoinhibition and Pn-peaks.

Here is what I will get: (1,000 watt Horti Blue with PL reflector)
http://www.bghydro.com/BGH/customkititems.asp?kc=HLPLMH10&eq=


Ballast:
The ballast effects the spectrum (quality) and irridiance (quantity) of PAR range photons. Ideally a digital ballast would be used to provide a more flat stream of electricity to the lamp, in turn that makes the lamp emit the same/similar quality and quantity more often.

I use a NextGen and really like it.

----------------------------------------------------------



My Plans for Testing Lamp, Reflector, Ballast and Combo:

I plan to test the Hoti Blue in the PL reflector with NextGen ballast by finding PPFD values per X inches over a 3x3 and 4x4 footprint. I plan to make irridiance spread maps of the footprints which will graphically show the hot-spots and their irridiance (see images below). This is going to be like the reflector testing thread here but with PPFD, I hope to have Pico's help with my project, I need to PM him because I was thinking about sharing a PPFD meter system and we both use the same testing methods (see below)...I welcome ANY LED maker/seller to send me products to test (on loan) and I will post the results.


My planed testing methodology:


PPFD measurements:
Li-Cor quantum sensor, the LI-190 (link); and the Li-Cor LI-250A Light meter (link).

Procedure:
I am going to copy Dr. Yoshi's method, that way my results should be considered valid in that my methods are accepted, however, I will use 24", 16", 12" and 10" distances for testing HID lamps:

I plan to start testing this setup in the next two months then I can present data, graphs, etc; and I want to test lots of lamps and reflectors and ballasts so I hope manufactures will send me free product on loan to test, I want to mimic for cannabis horticulture what Dr. Yoshi has done for reefing.

(see number six reference below)

The data plots for each reflector at the distances 24" and 30" are plotted as a surface graph, top view graph, and a % distribution graph to illustrate the intensity and spread at different points on the 36"X36" measuring grid, with data recorded at 3" intervals. The lamps are oriented so that they are parallel to the X-axis in the plots, with the center of the lamp aligned with (0,0). All measurements of distances are taken from the centerline of the lamp

Here are examples of irridiance spread over footprint, the top graph in each figure is from 24" and the graph below it in the same figure is from 30":

References:

1. “Importance of a Good Reflector,”
http://www.aquariumgarden.com/info.php?doc_base=articles/lights/reflector.php

2. “CanopyReflec,”
http://www.wetwebmedia.com/canopyreflec.htm

3. “DIY Guide to MH Halide Lighting Systems,”
http://www.personal.psu.edu/sbj4/aquarium/mh/mhlighting.html

4. “What’s In Your Metal Halide Reflector,”
http://blog.fragd.it/2009/03/10/whats-in-your-metal-halide-reflector/

5. “Analyzing Reflectors: Part 1 - Mogul Reflectors,”
http://www.advancedaquarist.com/issues/mar2003/feature.htm

6. “Analyzing Reflectors: Part 2 - Lumenbrite III, Lumenmax Elite, Lumenmax, and Lumenarc III,”
http://www.advancedaquarist.com/2009/1/review

7. “P.L. Reflector Models And Applications,”
http://www.pllight.com/horticultural/products/reflectors.php

 

[secondtry]

On the topic of UV-b:

As I wrote, adding UV-b when growing cannabis offers many benefits. The irridiance level used in a study with cannabis was about 375 uW/cm^2. Irridiance levels of up to ~420 uW/cm^2 have been recorded in the tropics near the equator at midday in the summer and UV-b levels up to about ~520 uW/cm^2 has been recorded at the top of a volcanic on Maui, Hi in the summer at midday. In the UK during summer the morning and evening sunlight is often in the range of 140 uW/cm^2. (average irridiances were taken from Francis at UVguide and the UVb meter users group).

I use ~10" deep "brooder" reflector/fixture with ceramic base to screw the UV-b lamp into. I use a step-down converter to run the 230v (EU) lamp in a 120v (US) wall socket. The brooder reflector/fixture has a big clamp on the back which I use to attach to my light mover so as the HID is moving spreading light so are the UV-b lamps (one of either side of HID reflector).

I try to provide irridiance levels of 200-400 uW/cm^2 over the whole canopy; to efficiently and trivially achieve those irridiances it takes high power mercury vapor lamps (e.g., reptile UV-b zoo lamps). I provide UV-b for 3-4 hours a day, that is about the time-frame where UV-b peaks in nature per day (around noon). The UV-b fluorescent lamps from PetSmart will not cut it.

The whole UV-b range is useful and should be provided, just like the whole PAR range should be provided. For that reason I use broad-brand UV-b lamps (i.e., Osram Ultra-Vitalux, 300 watt), not narrow-band UV-b lamps (e.g., ReptileUV Zoo Mega-Ray); please see the following image for a virtual of what I mean:

Francis over at UVGuide.co.uk has done extensive testing of UV-b lamps, and specifically the two zoo quality lamps I listed above. It's a good read and I posted some figures and data below which Francis, et al., compiled. The Osram is a great choice and when placed 18-24" from the canopy will provide 200-350 uW/cm^2 at core hotspot. I hang my lamps either 18" to 22" from canopy, the older they are the closer I hang them. When the Osram is placed 24" from canopy the core hotspot reaches about 240 uW/cm^2 (it's about 3-4" in width) and the irridiance down to about 20 uW/cm^2 reaches out to a width of about 3.5 feet.

http://www.uvguide.co.uk/zoolamps.htm

Osram Ultra-Vitalux lamps

The Osram lamps are flood lamps, producing an extremely wide beam of UVB radiation projected beneath the lamp. For most of its length, all radiation from 20 uW/cm² upward from the newly burned-in Osram lamp is contained in a roughly cylindrical zone over three feet wide, with a gradient towards its central axis.

At a distance of 2 feet, the beam (defined here as radiation from 20 uW/cm² upward, projecting from the lamp) is about 3.5 feet wide and reaches over 240 uW/cm² at its core. This is around the level recorded from direct mid-day sunlight in May, in the UK. At a distance of 3 feet, the beam is still 3 feet wide and the highest reading was just over 60 uW/cm2 in the centre here. The beam tapers gradually but at six feet from the lamp surface, 20uW/cm² (cited by one author as a minimum level recommended for green iguanas 27) is still available in a zone about 30 inches wide, with just over 30 uW/cm² being recorded at the centre of the beam.

The spread chart for the one-year-old Osram lamp shows, as might be expected, a scaled-down version of the UVB gradient seen with the new lamp. At a distance of 2 feet, the beam is not quite 2 feet wide and reaches nearly 100 uW/cm² at its core.

Images of Osram Ultra-Vitalux 300 watt:
(the heat from the Vitalux was nothing I had to worry about)

Reference:

"High UVB Output Mercury Vapour Lamps used in Zoos: The Osram Ultra-Vitalux and ReptileUV Zoo Mega-Ray Mercury Vapour Lamps on Test" UVGuide.co.uk (2006)
http://www.uvguide.co.uk/zoolamps.htm


HTH